DE20024022U1 - Uniform fluid intake, storage and distribution material - Google Patents

Abstract

The present invention provides a method of forming a multistrata absorbent structure, comprising: a) airlaying a 1st batt of fibers to be used in fluid distribution; b) airlaying a 2nd batt of fibers and a high absorbency material to be used in fluid storage over the 1st batt of fibers; c) airlaying a 3rd batt of fibers to be used in fluid acquisition over the 2 nd batt of fibers; and d) compacting the batts of fibers to form a multistrata absorbent structure comprising a fluid storage stratum between an acquisition stratum and a distribution stratum.

Description

Field of the invention

The The present invention is directed to improved absorbent fiber structures with separate layers (or strata) as areas for the liquid intake, storage and distribution directed. The structures serve to provide improved disposable, absorbent products such. Diapers, incontinence pads for To provide adults and sanitary napkins.

State of the art

absorbent Objects such. B. disposable diapers, incontinence pads for adults, sanitary napkins and the like generally with an absorbent core or storage layer provided to absorb body fluids and to keep. The absorbent core is usually between a liquid-permeable upper layer whose Function it is, the passage of the liquid to the core to allow, and a liquid-impermeable inserted back layer containing the liquid stops and prevents them from passing through the absorbent object to step through. An absorbent core (eg for Diapers and incontinence pads for adults) typically fibrous webs or webs made of frayed, loose, flake-dried, hydrophilic cellulose fibers are constructed. The core can also be superabsorbent polymer particles (SAP particles), Contain granules, flakes or fibers. additionally an absorbent article may contain a distribution layer, which helps to remove the liquid quickly from the receiving layer to transport the storage layer of the core. conventional absorbent products have separately formed layers for the recording, distribution and storage used, resulting in complicated and overloaded Production facilities leads. Therefore, there is a need for one absorbent product, in which the intake, distribution and Memory function all performed in a single integrated structure.

The Market demand for thinner and more comfortable absorbing Articles has increased. Such articles can be obtained be reduced by the thickness of the diaper core is reduced by the Amount of fiber material used in the core is reduced while the amount of SAP particles is increased, and by the core smoothed (calendered) or compressed, so that To reduce final gauge and thus increase the density. However, higher density cores absorb liquid not as fast as lower density cores because of the compaction the core to a smaller effective pore size leads. Accordingly, a suitable liquid absorption rate It is necessary to maintain a layer of low density and larger pore size over to provide the high density absorbent core with the uptake rate the liquid dispensed on the absorbent article to increase. Due to insufficient pore sizes have conventional absorbent structures at an inability suffered, large bursts of fluid to absorb. There is a clear need for absorbent Structures containing a recording layer with sufficient pore size have to absorb fluid thrusts better.

at a conventional multilayer absorbent structure with a recording layer, a distribution layer and a storage layer the recording layer absorbs the accumulating liquid and transfers them quickly by capillary action away from the wearer's skin (in the Z direction). Then meets the liquid on the distribution layer. The Distribution view is typically made of a higher density material and causes the fluid to move away from the skin Carrier (in the Z direction) and also laterally over the structure (in the X-Y directions) migrates. After all the liquid migrates into the storage layer. The storage layer contains in general high density cellulose fibers and SAP particles. The liquid is removed from the storage layer and in particular absorbed by the SAP particles contained therein.

Even though the conventional multilayer structure described above can be effective, there is a disadvantage of this arrangement, that due to the distribution layer being on the Skin of the wearer facing side of the storage layer There is a possibility that the liquid is due to the relatively low liquid retention capacity of the distribution layer to the skin of the wearer can, before it is absorbed by the storage layer. If the carrier moves, pressure is applied and can cause the liquid to be released and thereby makes the wearer wet again. Accordingly would it be desirable to provide a structure in which the liquid is absorbed immediately and gone transferred from the skin of the wearer in the Z direction where it can be absorbed into the storage layer while the problem that the fluid is the skin of the wearer touched again, minimized or eliminated.

Presentation of the invention

The The present invention provides a unitary absorbent structure with a fluid receiving layer; a liquid distribution layer; and a liquid storage layer between the receiving layer and the distributor layer ready. The recording, distribution and storage layers are each in fluid communication with each other.

Brief description of the drawings

1 shows a schematic cross section of a conventional multilayer absorbent structure.

2 Figure 14 shows a schematic cross section of one possible embodiment of the unitary, multi-layered absorbent structures of the invention.

3 Figure 12 shows a schematic cross-section of the path of liquid absorption by the unitized multilayer absorbent structures of the invention.

Detailed description the invention

The present invention encompasses a uniform, multizone, or multilayer absorbent structure comprising a receiving layer, which absorbs the discharged liquid and quickly through Capillary action away from the wearer's skin (in the Z direction); a memory layer with matrix fibers of higher density and SAP-particles; and a distribution view that is part of the excess Liquid that penetrates through the storage layer, absorbed and stops. As used herein, the terms "layers" and "layer" are intended to be refer to layered areas that make up the unitary structure is constructed. The layers of the unified structure are none Arrangement or laminate of preformed layers containing a multilayer Form structure. Instead, the unified structure is built by putting together the layers in a continuous way. The technology of laying in the airflow process is the preferred one Method for merging the layers of the uniform Structure of the present invention.

In According to one embodiment, the distribution layer comprises Fiber matrix material and causes the liquid to flow over laterally the structure (in the X-Y directions) and back to the Storage layer migrated where the liquid from the SAP particles is absorbed and held in the storage layer. This arrangement causes the fluid impinging on the structure pulled away from the user's skin and through the entire structure where it can be absorbed in the storage layer and thereby a lower tendency to accumulate or retain moisture at the interface of the structure to the skin of the wearer consists. This invention also includes an absorbent structure with a receiving layer, which is an enlarged Has pore size.

In In a preferred embodiment, the absorbent ones comprise Structures of the present invention at least three layers, all of which are in fluid communication with each other. These layers include: an (upper) fluid receiving layer, a (middle) liquid storage layer, and a (lower) Fluid distribution layer.

The (upper) liquid receiving layer may include: polyester (ie, PET) and / or synthetic homopolymer fibers; 0-10% SAP; and thermal or latex binder resin; In addition, they will typically have a basis weight of 20-120 g / m ² have. The (middle) liquid storage layer may comprise: flake-dried cellulose fibers and / or chemically modified cellulose fibers; 10-75% SAP; and a thermal binder resin; moreover, it will typically have a basis weight of 60-400 g / m ² . The (lower) liquid distribution layer may include: flake dried and / or chemically modified cellulose fibers; 0-10% SAP; and thermal and / or latex binder resin; moreover, it will typically have a basis weight of 20-200 g / m ² .

A second preferred embodiment of the invention four layers: a (top) receiving layer of synthetic fibers, a (upper middle) receiving layer of cellulose fibers, a (lower middle) storage layer and a (lowest) distribution layer.

The range of the total basis weight of these composite structures is 100-720 g / m ² with a SAP content of 10-75%. The preferred basis weight range (s) and SAP content will vary with the intended application. For feminine hygiene and light adult capacity incontinence applications, the basis weight and SAP content will tend towards the lower end of the ranges. For applications in infant diapers and high capacity adult incontinence applications, the preferred basis weight and SAP content will tend toward the upper end of the specified ranges.

The Recording layer is for a minimal fluid retention designed. In a preferred embodiment, (are) the matrix fiber (s) of the receiving layer comprise a synthetic fiber (fibers), which is at least two deniers big and able to to be connected with latex. Examples of suitable synthetic fibers include: polyesters, polyamides and polyolefins, e.g. B. polyethylenes and polypropylenes. In a further preferred embodiment The recording layer contains 3-40 matrix fibers Denier large, crimped PET fibers with a Cutting length of 3-12 mm.

The storage layer is characterized by a relatively high concentration of superabsorbent polymer (SAP). The types of superabsorbent polymers which can be used in this invention include e.g. B .: SAPs in their particle form such. For example, irregular grains, spherical particles, short fibers (staple fibers, staple fibers), and other elongated particles. The U.S. Patent Nos. 5,147,343 ; No. 5,378,528 ; No. 5,795,439 ; No. 5,807,916 ; and no. 5,849,211 describe various superabsorbent polymers and methods of making superabsorbent polymers. An example of a superabsorbent polymer-forming system are crosslinked acrylic copolymers of metal salts of acrylic acid and acrylamide or other monomers such as e.g. B. 2-acrylamide-2-methylpropanesulfonic acid. Many conventional granular superabsorbent polymers are based on poly (acrylic acid) which has been crosslinked during polymerization with any multifunctional co-monomer crosslinking agents which are well known in the art. Examples of multifunctional crosslinking agents are in the U.S. Patent No. 2,929,154 ; No. 3,224,986 ; No. 3,332,909 ; and no. 4,076,673 described. For example, crosslinked carboxylated polyelectrolytes can be used to form superabsorbent polymers. Other water-soluble polyelectrolyte polymers are known to be useful for the preparation of crosslinked superabsorbents, which polymers include: carboxymethyl starch, carboxymethyl cellulose, chitosan salts, gelatin salts, etc. However, they are usually not of a commercial scale due to their higher cost used to increase the absorbency of disposable absorbent articles. Superabsorbent polymer granules useful in the practice of this invention are commercially available from a number of manufacturers, such as: Dow Chemical (Midland, Michigan), Stockhausen (Greensboro, North Carolina) and Chemdal (Arlington Heights, Illinois). In a preferred embodiment, the SAP is a superficially cross-linked, acrylic acid-based powder such. Stockhausen 9350 or SX70.

cellulose, which has been modified to the degree of crimping and stiffness of the individual fluff cellulose fibers (eg Buckeye HPF modified Fluff cellulose) can increase in the storage layer in place of or in addition to the standard fluff cellulose fibers used to increase fluid absorption and retention to increase the invention.

By Distributing the liquid in the X-Y direction allows it the distribution layer that the superabsorbent particles in the storage layer, which is far from the point of liquid entry are removed, absorbing fluid. The distribution layer also serves, not directly from the SAP of the storage layer absorbed fluid in the Z direction away from the skin to pull the carrier.

The Matrix fibers of the distribution layer can be fluff pulp (Fluff pulp), modified fluff cellulose or a mixture include. In a preferred embodiment the cellulose fibers of the distribution layer modified to the stiffness reduce the fibers and thereby more easily compact the layer.

In a preferred embodiment of the invention the liquid distribution layer mainly made of cellulose fibers having a mean pore size which are smaller than those of the liquid receiving layer is, and have a pore size smaller is equal to the pore size of the storage layer. In general, a smaller mean pore size correlates with a higher density. The density of the distribution view is preferred greater than the density of the recording and storage layers. When the density of the distribution layer becomes larger is the density of the recording layer and the storage layer, can have a high fluid intake rate and a small stain size factor of the absorbent Low density structures as well as a high liquid retention property the structures of high density are achieved.

In a preferred embodiment, the layers of the claimed absorbent structures are formed as a flore. Preferably, the absorbent layers are airlaid on top of a low weight (ie 10-20 g / m ² ) cellulose cloth or similar backing layer which serves to contain the SAP powder during the fabric forming operation and thus clogging the fiber collection screen with SAP Prevent particles.

An air laid web (nap) is typically prepared by dicing or defibering a cellulosic pulp layer or layers, typically with the aid of a hammer mill, to provide discrete fibers. The singulated fibers are then fed by air to form heads on a flore forming machine. Examples of several machines for forming air laid webs (flore) are in detail U.S. Patent No. 5,527,171 (Soerensen). The forming heads may comprise rotating or shaking drums which serve to maintain the fiber separation until the fibers are pulled by vacuum onto a small hole condensing drum or a small hole forming conveyor (or forming wire). Other fibers, such as. Synthetic thermoplastic fibers may also be introduced into the forming head through a fiber dosing system comprising a fiber opener, a dosing unit and an air conveyor. Where two defined layers are desired, such as As a distribution layer of fluff pulp and a receiving layer of synthetic fibers, two separate mold heads can be used for each type of fibers. After the fibers have been air-laid, the resulting structure is densified and the fibers bonded together.

Typically, a calender roll is used to densify the resulting structure. The compaction can also take place before all layers have been laid in the air stream. z. For example, a first pile of air laid fibers may be densified to form a distribution layer having a density of between about 0.08 and about 0.20 g / cm ³ prior to air laying subsequent fibrous webs.

The Fibers of the recording, distribution and / or storage layers can by heat softening a thermoplastic binder be connected to the fabric fibers. The thermoplastic binder includes any thermoplastic polymer that is at temperatures can be melted, not comprising the cellulose fibers to damage. Preference is given to the melting point of the thermoplastic Tying material should be less than about 175 ° C. Examples of suitable thermoplastic materials include thermoplastic Microfibers, thermoplastic powders, binder fibers in spin form and Bicomponent staple fibers (short fibers). In particular, the thermoplastic Binding material z. As polyethylene, polypropylene, polyvinyl chloride, Be polyvinylidene chloride. Other synthetic fiber materials, which can be used in thermally bonded fabrics, are described below. The thermoplastic binders can with cellulose fibers in the molding machine for air laid tissue or the appropriate layers be added after their laying in the air stream.

alternative or additionally, the distribution and acquisition layers be joined together by applying a latex spray. Examples elastomeric polymers available in latex form, include butadiene-styrene, butadiene-acrylonitrile and chloroprene (neoprene). Other examples of synthetic polymers used in latex include polymers or copolymers of the alkyl acrylates, Vinylacetates such. B. ethylene vinyl acetate, and acrylics such as. B. Styrene Butadienacryl. For the purposes of industrial hygiene and elimination a solvent recycling step, the synthetic latex as a water-based emulsion rather than organic Solvent emulsion can be applied. Latexes, the in the present invention are useful, can by an emulsion polymerization of certain oleofins (ethylenically not saturated) monomers.

This emulsion polymerization can be carried out by conventional methods using any of a variety of anionic, nonionic, cationic, zwitterionic and / or amphoteric emulsifiers to stabilize the resulting latex, including alkyl sulfates, alkylaryl alkoxy sulfates, alkylaryl sulfonates and alkali metal and / or ammonium salts of the alkyl and alkylaryl polyglycol ether sulfates; oxyethylated fatty alcohols or oxyethylated alkylphenols as well as block copolymers of ethylene oxide and propylene oxide; cationic adducts of primary, secondary or tertiary fatty amines or fatty amine oxyethylates with organic or inorganic acids, and quaternary alkylammonium surfactant; and alkylamidopropyl betaines. The oleofine monomer may be a single type of monomer or may be a mixture of different oleofiner monomers, thus forming copolymer particles that are dispersed or emulsified in the aqueous phase. Examples of olefinic monomers that can be used to form latex polymers include C ₂ -C ₄ alkyl and hydroxyalkyl acrylates, such as C ₂ -C ₄ alkyl and hydroxyalkyl acrylates. Those selected from the group of propyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-hydroxybutyl acrylate, 2-hydroxypropyl acrylate, ethyl krylate and mixtures thereof are selected. Other examples are C ₁ -C ₄ alkyl or hydroxyalkyl methacrylates selected from the group of propyl methacrylate, n-butylmethyl acrylate, isobutyl methacrylate, 2-hydroxyethyl methacrylates, 2-hydroxypropyl methacrylates, ethyl methacrylate, methyl methacrylate, vinyl acetate, and mixtures thereof. Further compounds are mixtures of the abovementioned C ₂ -C ₄ -alkyl and hydroxyalkyl acrylates and C ₁ -C ₄ -alkyl or hydroxyalkyl methacrylates. Methods of applying the latex include coating, dipping, brushing, spraying, and foaming. In a preferred embodiment, the latex is applied by spraying. The latex resin can be applied before after densification of the fiber web.

Bi-component short fibers are due to a high melting temperature of the core polymer (typically Polyethylene terephthalate (PET) or polypropylene), that of a sleeve polymer of low melting temperature (typically polyethylene, e.g., Hoechst-Trevira Type 255 (Charlotte, NC)), modified polyethylene or copolyesters.

The Connected tissues can be smoothed a second time, to increase its strength or with a design or Pattern to be embossed. When thermoplastic fibers can be used, a Heißglätten can be used to give the fabric a patterned compound. water can be added to the fabric to, if necessary, maintain a specified and desired moisture content and so minimize dusting, or to build up static To reduce electricity. The finished tissue is then rolled up for future use.

The The following examples serve to illustrate the invention and not to limit their scope.

Examples

Examples of some preferred embodiments of the invention are described in Tables 1 and 2. The raw materials of the embodiments described in Tables 1, 2 and 3, unless otherwise indicated: Flakes cellulose: Buckeye Foley Fluff (Buckeye Technologies Inc., Memphis, TN) Bonding fiber: Hoechst-Trevira T-255 from Hoechst-Trevira (Charlotte, NC) Latex binder: AirFlex 192 from Air Products (Allentown PA) PET fiber: Type D2645 6 denier × 6 mm crimped fiber from Hoechst-Trevira (Germany) Material: 18 grams per square meter wet

example 1

Table 1 - Single Compaction Embodiment - Sample MJ998-MF-17 Flake cellulose (g / m ² ) Binder fiber (g / m ² ) SAP powder (g / m ² ) Latex binder resin (g / m ² ) PET fiber (g / m ² ) recording layer 0.0 0.0 0.0 6.0 34.0 storage layer 55 5 40 0.0 0.0 distribution layer 57 3 0.0 0.0 0.0

The material MJ998-MF-17 was formed on an M & J type airflow molding machine. The cellulose distribution layer was first applied to a cloth. The storage layer was then molded onto the spreading layer and then the receiving layer was formed on top of the storage layer. The resulting three-layer material was thermally bonded and then compressed by calendering to ³ to achieve an overall density of 0.142 g / cm.

Example 2

In an alternative embodiment, the distribution layer was first densified before the other layers were air-laid, and all layers were densified together. Table 2 - Double Density Embodiment - Sample MJ998-MF-18b Flake cellulose (g / m ² ) Binder fiber (g / m ² ) SAP powder (g / m ² ) Latex binder resin (g / m ² ) PET fiber (g / m ² ) recording layer 0.0 0.0 0.0 6.0 34.0 storage layer 55 5 40 0.0 0.0 distribution layer 57 3 0.0 0.0 0.0

The material MJ998-MF-18b was formed on a M & J type airstream molding machine. The cellulose distribution layer was first formed on a fabric and then by calendering to a density of 0.15 g / cm ³ compressed. The storage layer was then molded onto the distribution layers, and then the receptive layer was formed on top of the storage layer. The resulting three-layer material was compacted and then thermally bonded to ³ to achieve an overall composite material density of 0.081 g / cm.

Example 3

It is preferable that the cellulose fibers of the spreading layer are thermally bonded together. Table 3 describes a composite example in which a thermally bonded flake cellulose spreading layer overlies the storage layer and under the receiving layer. Table 3 - Absorbent structure with the distribution layer over the storage layer - Sample MJ998-MF-9 (Reference) Flake cellulose (g / m ² ) Binder fiber (g / m ² ) SAP powder (g / m ² ) Latex binder resin (g / m ² ) PET fiber (g / m ² ) recording layer 0.0 0.0 0.0 6.0 34.0 distribution layer 57 3 0.0 0.0 0.0 storage layer 55 5 40 0.0 0.0

The material MJ998-MF-9 was also formed on a pilot plant of the M & J type. This material reflects a structure described above in that the liquid storage layer is first molded. The spreading layer is formed on top of the storage layer, and then the receiving layer is formed on the top of the spreading layer. The flake cellulose in the distribution layer was Buckeye HPF fibers. This three layer structure was thermally bonded and compacted to ³ to achieve an overall density of 0.094 g / cm.

fluid absorption and fluid retention test

The The composite materials described above have been liquid uptake tests subjected. Each sample (with dimensions of 10 cm × 25 cm) was coated with a suitable coating material (cover material) wrapped and onto a lower fluid inlet test plate ("FIT" plate) with down-facing sieve or Carrier side placed. The center of the samples was marked.

Reception rate evaluations were performed by subjecting the test samples to three consecutive 10 ml infusions of 0.9% saline. The first infusion from 10 0.9% saline was poured as quickly as possible into the clear addition tube of the FIT plate without overflowing. The time from the moment of pouring to the moment the saline solution reached the test sample was measured. The stopwatch was stopped as soon as all the saline had passed through the bottom of the tube. The recorded time was the time taken by the upper layer for recording. After one minute intervals, the procedure was repeated with a second and third 10 ml infusion.

The uptake rate of each liquid infusion was determined according to the following formula:

The composite materials described above were also subjected to fluid retention tests by measuring the amount of 0.9% saline solution passing through the top layer of the structure from a stack of filter paper under a pressure of 6,89 mbar (0.1 psi) after each fluid infusion could be absorbed back. Samples were prepared for three separate measurements (each measuring 21.59 x 27.44 cm (8½ "x 11")). Each sample was placed on a plastic platform with fabric side down and its center marked. 10 ml of 0.9% saline (first infusion) was drained to the sample from a funnel at a distance of approximately 3.81 cm (1.5 ") above the center of the sample. The sample was left for 20 minutes. A stack of 12 filter papers was weighed and placed on the center of the wetted area and pressed with an applied circular weight. After two minutes, the filter papers were removed and weighed again. This procedure was repeated with a second infusion of 10 ml saline and a stack of 16 filter papers and a third infusion of 10 ml saline and a stack of 20 filter papers. The rewet value and the percent liquid retention were calculated from the first, second and third spouts according to the following formulas: Rewetting 1,2 or 3 = Weight of wet filter papers - weight of dry filter papers Percent Retention = (50 - rewet) / 50 × 100%

Further, the size of the liquid spot after the third infusion was recorded in the liquid retention test. The results are shown in Table 4. Table 4 - uptake rate and fluid retention test sample Take-up rate (ml / s) Liquid retention (%) Stain area 1st infusion 2nd infusion 3rd infusion 1st infusion 2nd infusion 3rd infusion cm ² Example 1 - MJ998-MF-17 3.7 1.6 1.4 99% 97% 86% 112 Example 2 - MJ998-MF-18b 7.5 6.1 4.9 99% 91% 73% 79 Example 3 - MJ998-MF-9 5.4 3.5 2.9 98% 79% 55% 95

One Comparison of MF-9 and MF-17 shows that the shift of the liquid distribution layer of the middle position (as in MF-9) to the lower position of the three-layered Structure (as in MF-17) the fluid retention capacity at the expense of some reduction in fluid intake rate and an increase in the size of the liquid spot significantly increased.

The Embodiment of the present invention with double Compaction, MF-18b, shows an improvement over MF-9 for the liquid uptake rate, the liquid retention ability and the spot size.

Additional examples

In the following examples, unless otherwise noted, the following raw materials are present: Standard fluff pulp: Foley Fluff. (Buckeye Technologies Inc., Memphis, TN) Elastic fluff pulp: HPF (Buckeye Technologies Inc., Memphis, TN) Compressible fluff pulp: ND416 (Weyerhaeuser Tacoma, WA) Superabsorbent powder: 1180 (Stockhausen Greensboro, NC) Bonding fiber: T-255, 2.8 dtex x 4 mm (Kosa, Charlotte, NC) PET fiber: T-224, 17 dtex x 6 mm (Kosa, Charlotte, NC) Latex binder: AirFlex 192 (Air Products, Allentown, PA)

The The composite materials described above were subjected to a liquid uptake test and a fluid retention test as above unless otherwise noted.

Examples 4 and 5 - acquisition layer matrix fibers

The Examples 4 and 5 compare the latex-linked flake cellulose fibers with latex-linked synthetic fibers in the acquisition layer an absorbent composite structure.

Example BU124-19 is an embodiment of the invention having a latex-bonded PET fiber receiving layer and example BU124-22 is identical to BU124-19, except that the receiving layer consists of latex-linked standard flake cellulose fibers. Table A1 - Absorbent structure with latex binder and fluff pulp in the receiving layer - Example BU124-22 distribution layer storage layer recording layer total below center above (g / m ² ) (g / m ² ) (g / m ² ) (g / m ² ) total Compressible pulp 69.3 0.0 0.0 69.3 28.5% Elastic pulp 0.0 43.7 0.0 43.7 18.0% SAP powder 0.0 55.9 0.0 55.9 23.0% bonding fiber 6.2 7.6 0.0 13.8 5.7% PET fiber 0.0 0.0 0.0 0.0 0.0% Standard Flake pulp 0.0 0.0 38.4 38.4 15.8% latex binder 0.0 0.0 6.8 6.8 2.8% excipient 15.0 0.0 0.0 15.0 6.2% total 90.5 107.2 45.2 242.9 100.0% Table A2 - Absorbent structure with latex binder and PET fibers in the receiving layer - Example BU124-19 distribution layer storage layer recording layer total below center above (g / m ² ) (g / m ² ) (g / m ² ) (g / m ² ) total Compressible pulp 69.3 0.0 0.0 69.3 28.5% Elastic pulp 0.0 43.7 0.0 43.7 18.0% SAP powder 0.0 55.9 0.0 55.9 23.0% bonding fiber 6.2 7.6 0.0 13.9 5.7% PET fiber 0.0 0.0 38.4 38.4 15.8% Standard Flake pulp 0.0 0.0 0.0 0.0 0.0% latex binder 0.0 0.0 6.8 6.8 2.8% excipient 15.0 0.0 0.0 15.0 6.2% total 90.5 107.2 45.2 243 100.0%

Table A3 shows the relative liquid uptake and retention capability of samples BU124-22 (with a standard latex-attached flake cellulose receptive latex layer) and BU124-19 (with a latex-bonded PET fiber receptive layer) Fluff pulp (BU124-22) and with PET fibers (BU124-19) as well as latex binder in the receiving layer variety Fluid Retention - 7 ml infusions Intake rate 3. 5 ml infusion 1st infusion 2nd infusion 3rd infusion (Ml / sec) BU124-22 74.1% 52.8% 38.1% 0.053 BU124-19 95.6% 71.5% 56.1% 0.18

Examples 6 and 7 - SAP in the middle layer compared with SAP in the lower layer of a three-layered uniform structure.

Examples 6 and 7 compare absorbent structures with SAP in the middle Layer compared to absorbent structures with SAP in the lower layer of a three-layered uniform structure.

Example X575 is a preferred embodiment of the invention with the SAP in the middle layer, Example X572 is similar to Example X575, except that the superabsorbent powder is placed in the lower layer. Table B1 - Absorbing Structure with SAP in the Middle Layer - Example X575 distribution layer storage layer recording layer total below center above (g / m ² ) (g / m ² ) (g / m ² ) (g / m ² ) total Compressible pulp 69.3 0.0 0.0 69.3 28.5% Elastic pulp 0.0 43.7 0.0 43.7 18.0% SAP powder 0.0 55.9 0.0 55.9 23.0% bonding fiber 6.2 7.6 0.0 13.8 5.7% PET fiber 0.0 0.0 38.4 38.4 15.8% latex binder 0.0 0.0 6.8 6.8 2.8% excipient 15.0 0.0 0.0 15.0 6.2% total 90.5 107.2 45.2 242.9 100.0% density 0.133 g / cm ³ Table B2 - Absorbing structure with SAP in the lower layer - Example X572 distribution layer storage layer recording layer total below center above (g / m ² ) (g / m ² ) (g / m ² ) (g / m ² ) total Compressible pulp 45.8 0.0 0.0 45.8 18.8% Elastic pulp 0.0 65.6 0.0 65.6 27.0% SAP powder 55.9 0.0 0.0 55.9 23.0% bonding fiber 7.6 7.9 0.0 15.5 6.4% PET fiber 0.0 0.0 38.4 38.4 15.8% latex binder 0.0 0.0 6.8 6.8 2.8% excipient 15.0 0.0 0.0 15.0 6.2% total 124.3 73.5 45.2 243.0 100.0% density 0.114 g / cm ³

Table B3 shows the fluid uptake and retention capacity of samples X575 and X572 Table B3 - relative performance of absorbent structures with SAP in the lower (X572) and middle (X575) layers sample Fluid Retention - 7 ml infusions Intake rate 3. 5 ml infusion 1st infusion 2nd infusion 3rd infusion (Ml / sec) X572 99.1% 72.3% 48.1% 0.171 X575 99.0% 90.4% 66.6% 0,255

Examples 8 and 9 - preferred Embodiments in comparison to commercially available thin sanitary napkins.

Examples Figures 8 and 9 compare several preferred absorbent structures this application with commercially available thin Sanitary napkins.

Examples X573 and X574 are preferred embodiments of the invention. They differ from the sample X575 only in the basis weight. Table C1 - three-layer absorbent structure - Example X573 Distribution layer storage layer recording layer total below center above (g / m ² ) (g / m ² ) (g / m ² ) (g / m ² ) total Compressible pulp 45.5 0.0 0.0 45.5 26.0% Elastic pulp 0.0 31.5 0.0 31.5 18.0% SAP powder 0.0 40.3 0.0 40.3 23.0% bonding fiber 4.5 5.5 0.0 10.0 5.7% PET fiber 0.0 0.0 27.7 27.7 15.8% latex binder 0.0 0.0 4.9 4.9 2.8% excipient 15.0 0.0 0.0 15.0 8.6% total 65.0 77.3 32.6 174.9 100.0% density 0.105 g / cm ³ Table C2 - three-layer absorbent structure - Example X574 distribution layer storage layer recording layer total below center above (g / m ² ) (g / m ² ) (g / m ² ) (g / m ² ) total Compressible pulp 59.6 0.0 0.0 59.6 27.7% Elastic pulp 0.0 38.7 0.0 38.7 18.0% SAP powder 0.0 49.5 0.0 49.5 23.0% bonding fiber 5.5 6.7 0.0 12.2 5.7% PET fiber 0.0 0.0 34.0 34.0 15.8% latex binder 0.0 0.0 6.0 6.0 2.8% excipient 15.0 0.0 0.0 15.0 7.0% total 80.1 94.9 40.0 215.0 100.0% density 0.124 g / cm ³

Table C3 shows the fluid intake and retention capability of the preferred embodiments of the invention compared to commercially available thin sanitary napkins. Table C3 - relative performance of Examples X573, X574, X575 and commercially available thin sanitary napkins sample basis weight Fluid retention - 7 ml infusions Intake rate 3. 5 ml infusion (g / m ² ) 1st infusion 2nd infusion 3rd infusion (Ml / s) X573 170 95.6% 62.7% 42.4% 0.164 X574 215 98.9% 79.4% 57.1% 0.195 X575 243 99.0% 90.4% 66.6% 0,255 brand A 368 80.0% 58.6% 44.3% 0,040 B 233 87.1% 68.6% 51.4% 0,068 C 250 81.4% 58.6% 38.6% 0,018

Examples 10 and 11 - Chemical modified flake cellulose in comparison with standard flake cellulose

Examples 10 and 11 compare structures with chemically modified cellulose and standard flake cellulose for the storage layer. Table D1 - Standard Flake Cellulose Absorbing Structure - Example MJ299-MF-2 distribution layer storage layer recording layer total below center above (g / m ² ) (g / m ² ) (g / m ² ) (g / m ² ) total Compressible pulp 61.8 0.0 0.0 61.8 28.1% Elastic pulp 0.0 0.0 0.0 0.0 0.0% Standard pulp 0.0 55.0 0.0 55.0 25.0% SAP powder 0.0 40.0 0.0 40.0 18.2% bonding fiber 3.3 5.0 0.0 8.3 3.8% PET fiber 0.0 0.0 34.0 34.0 15.4% latex binder 0.0 0.0 6.0 6.0 2.7% excipient 15.0 0.0 0.0 15.0 6.8% total 80.1 100.0 40.0 220.1 100.0% density 0.127 g / cm ³ Table D2 - cellulose cellulose absorbent structure - example MJ99-MF-6 distribution layer storage layer recording layer total below center above (g / m ² ) (g / m ² ) (g / m ² ) (g / m ² ) total Compressible pulp 61.8 0.0 0.0 61.8 28.1% Elastic pulp 0.0 55.0 0.0 55.0 25.0% Standard pulp 0.0 0.0 0.0 0.0 0.0% SAP powder 0.0 40.0 0.0 40.0 18.2% bonding fiber 3.3 5.0 0.0 8.3 3.8% PET fiber 0.0 0.0 34.0 34.0 15.4% latex binder 0.0 0.0 6.0 6.0 2.7% excipient 15.0 0.0 0.0 15.0 6.8% total 80.1 100.0 40.0 220.1 100.0% density 0.126 g / cm ³

Table D3 gives the fluid intake and retention capabilities for Examples MJ299-MF-2 and MJ299-MF-6. The test procedure used for Table D3 differs from the above fluid intake and fluid retention procedures in that multiple 10 ml 0.9% saline infusions are used in both the fluid intake and fluid retention tests. Table D3 - Relative Efficiency of the Absorbent Structure with Standard Flake Cellulose (MJ299-MF-2) and Cellulosic Elastic Cellulose (MJ299-MF-6) variety Fluid Retention - 7 ml infusions Intake rate 3. ml infusion 1st infusion 2nd infusion 3rd infusion (Ml / sec) MJ299-MF-2 98.6% 76.6% 42.8% 0.9 MJ299-MF-6 98.8% 73.9% 72.0% 1.5

Example 12 - preferred embodiment in comparison with conventional infant diapers

example 12 compares several preferred absorbent structures of these Use with commercially available toddler diapers.

Example MJ998-HMF-3 is an embodiment of the invention designed for a core / female layer insert of a toddler diaper. Table E1 - Absorbent structure suitable for use in diapers - Example MJ998-HMF-3 distribution layer storage layer recording layer total below center above (g / m ² ) (g / m ² ) (g / m ² ) (g / m ² ) total Compressible pulp 95.0 0.0 0.0 95.0 20.4% Elastic pulp 0.0 0.0 0.0 0.0 0.0% Standard pulp 0.0 105.0 0.0 105.0 22.6% SAP powder 0.0 180.0 0.0 180.0 38.7% bonding fiber 5.0 15.0 0.0 20.0 4.3% PET fiber 0.0 0.0 42.5 42.5 9.1% latex binder 0.0 0.0 8.0 8.0 1.7% excipient 15.0 0.0 0.0 15.0 3.2% total 115.0 300.0 50.5 465.5 100.0% density 0.122 g / cm ³

Table E2 shows the fluid uptake rate and fluid retention test results for sample MJ998-HMF-3 and several commercially available diapers. The test procedures are similar to those of the other examples, except that all fluid infusions are 50 ml of 0.9% saline and the MJ998-HMF-3 was cut to a 10 cm x 25 cm section. Table E2 - Performance of Example MJ998-HMF-3 several 50 ml saline infusions sample basis weight Liquid retention (%) Take-up rate (ml / s) MJ998-HMF-3 (g / m ² ) 477 1st infusion 99.9% 2nd infusion 99.8% 3rd infusion 99.5% 3rd infusion 3.7 commercial D 622 99.9% 96.8% 79.8% 2.4 commercial E 792 99.9% 99.0% 95.9% 1.8 commercial F 522 99.5% 96.9% 87.3% 2.9 commercial G 840 96.4% 79.1% 57.2% 2.5

Example 13

Table F compressive force PET HPF Foley Fluff ND-416 0 psi 0,070 0.032 0.032 0,038 450 PSI 0.094 0,099 0,100 0.113 900 PSI 0,100 0,117 0.126 0,170 1350 PSI 0.105 0,133 0.161 0.198

The Table F presents a comparison of the reaction of the various Flake cellulose fibers and a PET fiber to a given compressive force The fibers in Table F are: a 15 denier x 6 mm x 1.57 Ripples / cm (4 crimps per inch) measuring PET fiber from Kosa (Salisbury, NC); HPF, a chemically stiffened flake cellulose fiber from Buckeye Technologies; Foley Fluff, a standard flake cellulose fiber from Buckeye Technologies; ND-416, a chemically softened flake cellulose fiber from Weyerhaeuser (Tacoma, WA).

A mixture with a 90 g / m ² sample of each fiber at 10 g / m ^{2 of} a T-255 binder fiber was opened and formed in a stream of air into a 100 g / m ² fiber pile. The batt was bonded in a hot air oven. Separate portions of each of the materials were subjected to a compressive force of 0 psi, 450 psi, 900 psi and 1350 psi for one minute. The gauge block of each compressed sample was measured to determine the density. The density as a function of compressive force is shown in Table F. This table shows that the various fibers will provide a bonded airlaid material with a density that depends on the applied compressive force.

Consequently becomes a compressed unitary structure with a PET fiber comprehensive upper layer and a Buckeye HPF fibers middle layer and a Weyerhaeuser ND-416 fibers comprehensive lower layer do not have a constant density from top to bottom. Instead, the data contained in Table F shows that three-level density gradient will occur in the compressed structure wherein the upper PET layer has the lowest density and the lower ND-416 layer has the highest density.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

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Claims (23)

A unitary absorbent structure comprising: a) a fluid acquisition layer comprising polyester and / or synthetic homopolymer fibers, or fluff pulp or synthetic fibers, and a thermal and / or latex binder, the fluid acquisition layer having a basis weight of between 20 and 120 g / m ² b ) a liquid distribution layer comprising flake cellulose and / or chemically modified cellulosic fibers and a thermal and / or latex binder having a basis weight of between 20 and 200 g / m ² ; and c) a liquid storage layer between the receiving layer and the distribution layer, wherein the liquid storage layer comprises 10 to 75 wt% of superabsorbent polymer and has a basis weight of between 60 and 400 g / m ² , wherein each of the receiving layer, the storage layer and the distribution layer in liquid communication and wherein the density of the distribution layer is greater than the density of the recording layer and the density of the storage layer. Uniform absorbent structure according to claim 1, wherein the distribution layer has a density which is at least twice the total density of recording and storage layer is. Uniform absorbent structure according to claim 1 or 2, wherein the unitary structure no build or laminate preformed, is a multilayer structure forming layers, but the unified structure through steadily merged Layers, preferably by laying in the air stream, is constructed. A unitary absorbent structure according to claim 3, wherein the layers are air-laid on top of a support layer, preferably on the top of a cellulosic fabric having a basis weight of between 10 and 20 g / m ² . Uniform absorbent structure according to one of Claims 1 to 4, wherein the average elasticity each layer in a gradient towards the recording layer decreases to the distribution layer. Uniform absorbent structure according to one of preceding claims, wherein the receiving layer a aqueous latex binder resin, two-component fibers or contains a mixture of them. Uniform absorbent structure according to one of preceding claims, wherein the receiving layer synthetic Includes fibers having a size of at least Own 2 deniers. Uniform absorbent structure according to one of preceding claims, wherein the receiving layer further a binder which is selected from the group is made of two-component fibers, polyolefin powder and their Mixtures exists. Uniform absorbent structure according to one of preceding claims, wherein the receiving layer of polyethylene terephthalate (PET) fibers with a size of at least 2 denier. Uniform absorbent structure according to one of Claims 1 to 8, wherein the receiving layer curled PET fibers of 3-15 denier size with a cut length of between about 3 and about 12 mm. Uniform absorbent structure according to one of preceding claims, wherein the receiving layer is a first sublayer with cellulose fibers and a second sublayer comprising synthetic fibers, and wherein the first sub-layer closer to the storage layer than the second sub-layer. Uniform absorbent structure according to one of preceding claims, wherein the storage and distribution layer each contain thermoplastic binder fibers. Uniform absorbent structure according to one of preceding claims, wherein the storage layer is cellulose fibers and superabsorbent polymer. A unitary absorbent structure according to any one of the preceding claims wherein the storage layer comprises cellulosic fibers modified to reduce the crimp and / or stiffness of the fibers to increase. Uniform absorbent structure according to one of preceding claims, wherein the average pore size the distribution layer is less than the average pore size the recording layer and less than or equal to the middle one Pore size of the storage layer. Uniform absorbent structure according to one of Claims 1-15, wherein the average pore size the distribution layer less than the average pore size from both the acquisition and storage layers. Uniform absorbent structure according to claim 1, wherein the average pore size of the Distribution layer is less than half the average Pore size of the receiving and storage layer. Uniform absorbent structure according to claim 1, wherein the average pore size of each layer in a gradient in the direction from the receiving layer to the distribution layer decreases. Uniform absorbent structure according to one of Claims 1-18, wherein the distribution layer is cellulose fibers which have been modified to increase the stiffness of the fibers reduce. Uniform absorbent structure according to one of Claims 1-19, further a tissue layer in contact comprising the surface of the distribution layer, the turned away from the storage layer. Diaper, which is the uniform absorbent structure one of claims 1-20. Sanitary napkin containing the uniform absorbent Structure according to any one of claims 1-20. Incontinence pad for adults, which the unitary absorbent structure according to any one of claims 1-20 includes.